The present invention relates to an apparatus for detecting foreign matters that might be present in a liquid. More particularly, this invention relates to an apparatus for detecting stably and efficiently undesirable, minute foreign matters that might be present in medical fluids filled in transparent containers such as injection ampoules and vials.
Medical fluids in transparent containers such as injection ampoules and vials often contain such foreign matters as glass chips, granules, and fibers. The presence of such foreign matters is not desirable from a standpoint of quality, and it is necessary to reject those containers containing foreign matters by inspecting all the transparent containers filled with medical fluids.
The following method has been employed up to date for detecting the presence of minute foreign matters in medical fluids filled in transparent containers. A transparent container to be inspected is rotated at a high speed, and then brought to a standstill quickly, permitting foreign matters to suspend and swirl together with the fluid. The container is illuminated and the light which has passed through the fluid is received by an optical detector. Judgement for acceptance or rejection is made according to the degree of decrease in light received. Judgement for acceptance or rejection can also be made by measuring with an optical detector the quantity of light scattered by foreign matters in the fluid. In this method it is necessary that the transparent container to be inspected should be positioned in alignment with the optical axis of the optical detecting unit made up of a light source, lenses, and a detector. In the conventional apparatus the optical detecting unit which illuminates and receives light is unmovably mounted and the transferring board which feeds the containers continuously is mounted for intermittent rotary movement. The container to be inspected is stopped temporarily on the above-mentioned optical axis. Such temporary stopping of the container makes it necessary to move the container by mechanical action within a short time of an intermittent moving action. The transferring speed cannot be increased without sacrificing the stability of the container to be inspected. Mechanism becomes complex for stabilization of the container and the inspection capacity is low.